The invention relates to a waveguide system.
A waveguide system takes light from one or more light sources and distributes the light to one or more remote locations. The system operates by reflecting light from internal surfaces of the waveguide to send the light from the light source to the remote location. The angle at which the light hits the internal surface of the waveguide determines whether the light is reflected or passes through the surface. The light may be sent, for example, to a headlamp or stop light of an automobile.
In one general aspect, a waveguide system includes a waveguide and an external reflector. The waveguide includes at least one lenslet array, a rear region, and a light input region. The rear region is configured to leak light and the external reflector is positioned in the vicinity of the rear region and is configured to reflect the light leaked through the rear region back into the rear region. The waveguide may include a light source that directs light into the waveguide.
Embodiments may include one or more of the following features. For example, the waveguide may include a front lenslet array having individual lenslets with a first radius of curvature and the rear region may include a rear lenslet array having individual lenslets with a second radius of curvature. The first radius of curvature may be selected so that light from the light source is reflected in the direction of the rear lenslet array. The first radius of curvature also may be selected so that light from the light source is reflected in the direction of the rear lenslet array at an angle with the rear lenslet array such that the light passes through the rear lenslet array.
The external reflector may be positioned adjacent to the rear lenslet array and may define a focusing distance between the reflector and front lenslet array. In general, the focusing distance (i.e., the focal length) depends upon the front and back radii of the lenslets and the distance between the front and rear surfaces. The focusing distance may be selected to focus the light passing through the rear lenslet array in a forward direction. The focusing distance also may be set to focus the light in a wide or narrow cone in front of the front lenslet array. The external reflector may be a material that reflects light directly, such as a polished metal, or a material that reflects light diffusely, such as paper or roughened plastic.
In another general aspect, an object may be illuminated with a waveguide system by directing a beam of light into a waveguide that includes a light input region, a front lenslet array having individual lenslets with a radius of curvature, and a rear surface. The beam of light reflects off of the front lenslet array and a portion of the beam of light passes through the rear surface so that the portion leaks out of the waveguide. The portion that leaks is then reflected transversely by an external reflector back into the waveguide.
Embodiments may include one or more of the following features. For example, reflecting the portion of light from the external reflector may include focusing the portion of the light on the object to be illuminated by positioning the reflector a focusing distance from the front lenslet array (i.e., positioning the reflector at or near the focal plane so that light goes to the object to be illuminated). The reflector position may be set to focus the beam of light in a wide or narrow cone in front of the front lenslet array.
Another general aspect features a visor waveguide lighting system. The system includes a waveguide, an external reflector, a light input region, and a light source.
The waveguide includes a front lenslet array having a first radius of curvature, a rear lenslet array having a second radius of curvature, and a light input region. The first radius of curvature causes light from the light source to be internally reflected in the direction of the rear lenslet array at an angle with the rear lenslet array such that the light leaks through the rear lenslet array and the second radius of curvature causes light reflected off of the front lenslet array to leak through the rear lenslet array.
The external reflector is positioned in the vicinity of the rear lenslet array at a focusing distance from the front lenslet array. The focusing distance is a distance that causes light passing through the rear lenslet array and the front lenslet array to be focused in a cone in front of the front lenslet array.
The low profile waveguide system offers the considerable advantage of combining in a single device the functions of a waveguide, a lens, and an external reflector. The waveguide system has a narrow profile, which allows it to be used in tight spaces such as, for example, a visor, instrument cluster, running board, or step-up board of an automobile. It also offers the advantage of reduced manufacturing costs. Also, in simple optical systems, such as those including a point source of light and a thin lens, light reflected at the focusing distance is collimated by the lens.
Other features and advantages will be apparent from the following description, including the drawings, and from the claims.